Topic: Strange noise from the front end

[.RJ]

I've got my CB750 on the road, after a year of sporadic restoration.  Everything is pretty good although its got a strange noise in the front end that I've never heard before.  It only shows up at low speeds, under braking or going over speed bumps (fork compression) and there's an audible groaning and vibration through the clipons.  Anyone ever heard something like this?  Front brake has new piston/seal and doesnt seem to be dragging and steering head bearings are new (tapered).

I'm going to take the wheels/forks off and double check everything, but if I can get some ideas, that will be a little easier.

[Lumbee]

...get the front end up in the air and spin the wheel by hand then apply the brake.  Do this a few times and see if its dragging any.  Sounds like drag to me..

[KB02]

I'd almost say wheel bearing itself might be going bad.

...get the front end up in the air and spin the wheel by hand then apply the brake.  Do this a few times and see if its dragging any.  Sounds like drag to me..

Check out the wheel bearings while you have it in the air. Feel for smoothness and wobble.

[scondon]

Cables rubbing against the headlight shell. Can feel it in the bars and it groans

[Johnie]

I had a noise like a rattle on bumps too.  It was the front brake caliper bumping up and down.  I adjusted that drag screw and it went away.  Grab that caliper and see if you can shake it up and down.  If not, then that is not your problem.

[.RJ]

The nut that secures the caliper adjuster screw/spring had worked loose (or maybe I never tightened it) and the caliper wasnt lined up to the disc anymore.  The outside pad had also acquired a bunch of FOD and it was sticking in the bore too.  I havent ridden it yet, but I wasnt able to replicate the noise rolling it in the garage like before so I think thats it.

Its always the little things...

Now if I could get the brakes to stop squealing, that'd be nice.

[drdreas]

I'm experiencing the exact same groaning/vibration. Where you able to fix the problem?

[.RJ]

I'm experiencing the exact same groaning/vibration. Where you able to fix the problem?

Most of it was in the brake arm adjustment.  Its not totally gone away though, but 90%.  I think the pads (EBC) are a little thicker than they need to be and cause a little binding of the brake arm and it causes the vibration.

[drdreas]

I attempted to adjust the caliper position, but when I loosened the locknut and loosened the caliper adjustment screw, the caliper didn't move. Instead the screw just got loose and the caliper stayed where it is. Should the caliper and arm pivot freely? Did you run into this problem?

[.RJ]

Take the caliper off the arm, and get the brake piston bottomed out - make sure the arm is centered with the rotor, and reassemble.

[drdreas]

Ok, thanks. Would I need to remove the front wheel to do this, and can I do it without draining and re-bleeding the brake system?

[.RJ]

Ok, thanks. Would I need to remove the front wheel to do this, and can I do it without draining and re-bleeding the brake system?

No need to remove the front wheel, you can get a 3/8" drive 8mm hex socket through the wheel spokes (may need to roll the bike a bit to get them both).  You dont need to take the brake line off of the caliper, although it may help to get the brake line itself loose (I dont remember if there is anything attached to the stock line - i never had one on my 750) to move the caliper out of the way to eyeball the mount.  To push the piston back in, its generally easiest to put a piece of clear vacuum tubing on the bleeder, and then crack it open and push the piston back - with the bleeder open there wont be any resistance.  Check to make sure there's enough fluid in the master cylinder so that it doesnt go low or dry when you pump the brake pads back up to the rotor though.